Of all the surgical procedures currently performed on patients with cerebral
palsy (CP), selective dorsal rhizotomy (SDR)
has undergone more thorough scientific scrutiny than any other
(including orthopedic surgery). Accumulated evidence and our own
experience indicate that SDR is an excellent option for selected
patients with spastic
cerebral palsy. We believe parents and
patients should inquire about SDR as a part of the management of CP
before the patient undergoes orthopedic
SDR involves sectioning (cutting) of
some of the sensory nerve fibers that come from the muscles and
enter the spinal cord.
Two groups of nerve roots leave the
spinal cord and lie in the spinal canal. Theventral spinal
roots send information to the muscle; the dorsal spinal
roots transmit sensation from the muscle to the spinal cord.
time of the operation, the neurosurgeon divides each of the
dorsal roots into 3-5 rootlets and stimulates each rootlet
electrically. By examiningelectromyographic (EMG)
responses from muscles in the lower extremities, the
surgical team identifies the rootlets that cause spasticity.
The abnormal rootlets are selectively cut, leaving the
normal rootlets intact. This reduces messages from the
muscle, resulting in a better balance of activities of nerve
cells in the spinal cord, and thus reduces spasticity.
Different surgical techniques are utilized to perform SDR.
Neurosurgeons typically perform SDR after removing the lamina ( laminectomy )
from 5-7 vertebrae. That technique was also used at the St.
Louis Children's Hospital Cerebral Palsy Center to
perform SDR on over 140 children with CP. However, we were concerned
about possible problems that can arise from removal of such a large
amount of bone from the spine. Additionally, because of the
extensive removal of the bone, we could not offer SDR to children
with weak trunk muscles or to adults.
In 1991, we developed a less invasive surgical technique,
which requires removal of the lamina from only 1-2 vertebrae. We
refined the technique further and currently remove the lamina from a
single lumbar vertebra (Figure A&B).
SDR begins with a 1- to 2-inch
incision along the center of the lower back just above the
a portion of the lamina are removed to expose the spinal
cord and spinal nerves. Ultrasound and
an x-ray locate the tip of the spinal cord, where there is a
natural separation between sensory and motor nerves. A
rubber pad is placed to separate the motor from the sensory
nerves. The sensory nerve roots that will be tested and cut
are placed on top of the pad and the motor nerves beneath
the pad, away from the operative field.
sensory nerves are exposed, each sensory nerve root is
divided into 3-5 rootlets. Each rootlet is tested with EMG,
which records electrical patterns in muscles. Rootlets are
ranked from 1 (mild) to 4 (severe) for spasticity. The
severely abnormal rootlets are cut. This technique is
repeated for rootlets between spinal nerves L2 and S2. Half
of the L1 dorsal root fibers are cut without EMG testing.
When testing and cutting are
complete, the dura
closed, and fentanyl is
given to bathe the sensory nerves directly. The other layers of
tissue, muscle, fascia,
are sewn. The skin is closed with glue. There are no stitches to be
removed from the back. Surgery takes approximately 4 hours. The
patient goes to the recovery room for 1-2 hours before being
transferred to the intensive care unit overnight.
We believe that our selective dorsal rhizotomy procedure has these
significant advantages over others:
of spinal deformities in later years
Decreased post-rhizotomy motor weakness
Reduced hip flexor spasticity
by sectioning the first lumbar dorsal
Shorter-term, less intense back pain
Earlier resumption of vigorous physical therapy
The dorsal rhizotomy is a long and complex neurosurgical procedure.
As in other major neurosurgical procedures, it presents some risks.
Paralysis of the legs and bladder, impotence, and sensory loss are
the most serious complications. Wound infection and meningitis are
also possible, but they are usually controlled with antibiotics.
Leakage of the spinal fluid through the wound is another risk.
Abnormal sensitivity of the
skin on the feet and legs is relatively common after SDR, but
usually resolves within 6 weeks. There is no way to prevent the
abnormal sensitivity in the feet. Transient change in bladder
control may occur, but this also resolves within a few weeks. A few
of our patients have experienced urinary
tract infections and pneumonia.
more than 2,000 selective dorsal rhizotomy patients, only one adult
patient had a spinal fluid leak that required surgical repair. A few
children had spinal fluid collection under the skin but no surgery
was needed. One patient developed anugulation of the spine (kyphosis)
that required spine fusion. There was no long-term complications in
any of patients who underwent surgery as early as 1987. Our results
indicate the long-term safety of selective dorsal rhizotomy.
present, SDR is the only surgical procedure that can provide
permanent reduction of spasticity in CP. In our patients with spastic diplegia SDR
always reduced spasticity, and recurrences have been rare. Return of
spasticity in later years is highly unlikely after its reduction
over many years.
In patients with spastic quadriplegia,
however, SDR can fail to reduce spasticity. Recurrence of spasticity
is relatively common in severely involved nonambulatory patients
with spastic quadriplegia. In patients who can walk with an
assistive device, the risk for recurrent spasticity is less than in
nonambulatory patients, and even if it does recur, it is less severe
than before the operation.
It is our opinion that patients with cerebral
palsy do not depend on spasticity for any activities. Their case is
different from that of patients with spasticity associated with
spinal cord injury, in whom the spasticity sometimes does help with
standing and taking steps.
does not cause permanent weakness. However, patients will experience
transient motor weakness that may last a few weeks to months after
SDR. It should be remembered that a varying degree of motor weakness
is always present in cerebral palsy. When spasticity is reduced or
eliminated, the motor weakness underlying spasticity becomes more
noticeable, but the impression that SDR produces motor weakness is
Patients who walk independently always resume
independent walking within a few weeks after SDR. Patients who walk
with crutches will also resume crutch walking within several weeks
after SDR. Patients who walk well with a walker prior to selective
dorsal rhizotomy resume assisted walking within several weeks.
Patients who use a walker and assistance require much longer to
resume the level of walking they were capable of before SDR.
After spasticity is reduced, it becomes easier for
patients to increase strength with therapy and exercise. Adolescents
and adults can start treadmill and other types of exercise that were
impossible before SDR.
It is important to note that selective dorsal
rhizotomy does not result in floppy extremities, even immediately
after the operation.
Motor Function: SDR
results in improvements in sitting, standing, walking, and balance
control in walking. In three randomized studies of changes in gross
motor functions after SDR, two of the studies showed improvements
and one did not find significant benefits from SDR. All three
studies are, however, far short of conclusive. They assessed
outcomes using measures of gross motor function, which do not allow
assessment of changes in quality of motor functions or of children
whose impairment is relatively mild. Also, the follow-up studies of
these patients were too short to address the long-term benefits of
SDR, the effects of reduced spasticity on deformities, and the need
for orthopaedic surgery. In our view, the study by McLaughlin et
al., which failed to find any beneficial effect from SDR, is flawed
by various limitations, so no conclusion can be drawn from it.
Typically, improvements in motor function are most
noticeable during the first 6 months after SDR. After that,
improvements are slow but steady. In children, these improvements
can continue up to 10 years of age. In adults and adolescents,
improvements continue for approximately 2 years after SDR.
with cerebral palsy almost invariably have some deformities in the
lower extremities. Common deformities are hip subluxation,
hamstring and heel cord contractures,foot
deformities, and in-toeing. These deformities can be
improved by selective dorsal rhizotomy.
Hip subluxation can progress if left untreated. In
most patients, selective dorsal rhizotomy can halt the progression;
certainly it does not exacerbate or increase the risk of hip
subluxation. However, some children under 5 years of age who have
poorly developed hip joints do show progression of hip subluxation
regardless of treatment.
Selective dorsal rhizotomy reduces the severity of
hamstring and heel cord contractures. It is common to see
improvements in in-toeing gait and in other abnormal gait patterns
after SDR. Also, the lack of spasticity makes it easy to stretch the
tight muscles. When contractures have been present for years,
however, the affected muscles and tendons are shortened. It takes
many months to improve such contractures, and in older children and
adults, it is often impossible to do so except through surgical
Early selective dorsal rhizotomy, at 2-4 years of
age, can prevent the development of deformities. For this reason, we
favor early surgery. Also, SDR will reduce deformities and makes it
easier to treat deformities later with orthopaedic surgery.
Orthopedic Surgery: Many
patients with spastic cerebral
palsy require multiple orthopaedic
operations. Our study showed that early SDR may reduce the rate of
subsequent orthopedic procedures. It is important to remember that
deformities are due not only to spasticity but also to motor
impairment and consequent limited muscle stretching in daily
activities. That is, muscles without spasticity can still develop
contractures if they are not used and stretched fully. Therefore,
many patients will still require follow-up with orthopaedic surgeons
We favor SDR prior to
orthopaedic surgery. Muscle and tendon
increase a range of joint movements but weaken the muscles
permanently. Since SDR can increase the range of joint movement
without causing muscle weakness, we recommend SDR prior to muscle
releases. Persistent muscle and tendon contractures after SDR are
treated with vigorous stretching, night splints, and serial casting.
If all the nonsurgical treatments fail to resolve the contractures,
we recommend orthopedic surgery as a last resort.
Upper Extremity Functions: Selective
dorsal rhizotomy is performed to improve the lower extremity
functions, but it can also improve the gross range of motion of the
upper extremities. It does not improve fine motor skills. The upper
extremity improvements are seen in children with relatively severe
quadriplegic cerebral palsy. If the upper extremity involvement is
mild, SDR will not result in noticeable improvements.
Potty Training: Spastic cerebral
palsy can be associated with small bladder capacity and also with
difficulties in sitting, which can delay potty training in young
children. From time to time, we have seen children complete potty
training soon after selective dorsal rhizotomy.
Cognitive Improvements: We
have seen children who showed marked changes in cognitive functions
after SDR, and in our earlier study we found significant increase in
the speed of visual recognition.
Speech Improvement: Selective
dorsal rhizotomy can be followed by significant improvements of
speech. We attribute this to improved sitting posture, reduced
distraction by spasticity, and improved cognitive functions.
However, it is difficult to predict which patients will show speech
Emotional Improvements: Parents
often note that their children become much less irritable and more
loving after selective dorsal rhizotomy. We attribute this to
decreased mental distraction by tight muscles.